Apparatus for dynamically analyzing an electronic fuel injection system and the associated engine parts

ABSTRACT

Defect detecting apparatus for use with an internal combustion engine comprising means for sensing at least the speed, load condition, and ambient temperature of the internal combustion engine; fuel injection means injecting a variable amount of fuel into the cylinder of the engine in response to at least one control signal; control means for generating the control signal in response to the sensing means; and defect detecting means responsive to at least the sensing means, the fuel injection means, and the control means for dynamically detecting any defects within the sensing means, the fuel injection means, the control means, and the engine while the engine is running without interfering with the operation of the engine, the sensing means, the fuel injection means and the control means. Reference signal generating means may be substituted for the above control means to isolate the defect in either (1) the sensing means, the fuel injection means, or the engine or (2) the control means. Further, the signal generating means may be used as a control means to control the operation of the fuel injection system and run the engine.

United States Patent Kaireit [451 Nov. 18, 1975 APPARATUS FORDYNAMICALLY ANALYZING AN ELECTRONIC FUEL INJECTION SYSTEM AND THEASSOCIATED ENGINE PARTS [75] Inventor: Manfred Gustav Kaireit, West PalmBeach, Fla.

[73] Assignee: Gerold J. Harbeke, Lake Worth,

Fla.

22 Filed: Jan. 31, 1974 21 Appl No.: 438,446

Related US. Application Data [63] Continuation of Ser. No. 237,828,March 24, i972.

abandoned.

[52] US. Cl 73/119 A [51] Int. Cl. G01M 15/00 [58] Field of Search 73/l19 A, 1173, 118

[56] References Cited UNITED STATES PATENTS 3,463,130 8/l969 Reichardtet al. 73/l 19 A UX 3,732,492 5/1973 Geul 73/1 l9 A X PrimaryE.\'aminer.lerry H. Myracle [57] ABSTRACT Defect detecting apparatus foruse with an internal combustion engine comprising means for sensing atleast the speed, load condition, and ambient tempera ture of theinternal combustion engine; fuel injection means injecting a variableamount of fuel into the cylinder of the engine in response to at leastone control signal; control means for generating the control signal inresponse to the sensing means; and defect detecting means responsive toat least the sensing means, the fuel injection means, and the controlmeans for dynamically detecting any defects within the sensing means,the fuel injection means, the control means, and the engine while theengine is running without interfering with the operation of the engine,the sensing means, the fuel injection means and the control means.Reference signal generating means may be substituted for the abovecontrol means to isolate the defect in either (1) the sensing means, thefuel injection means, or the engine or (2) the control means. Further,the signal generating means may be used as a control means to controlthe operation of the fuel injection system and run the engine.

46 Claims, 13 Drawing Figures comm/m0 FUEL SENSORS TL UNIT 52: INJECTORI L- 2o 30; J 28 REFERENCE I ANALYZER GENERATOR I is L/m I L USE Pawn?!Nov. 12%, .975 5116i? 1 of6 3,919,885

10 I2 24 T6 2s COMMANO FUEL SENSORS UNIT }Z INJECTOR T T 22 I REFERENCEANALYZER L OENERATOR I L/I4 I ELECTRIC F l G. [A FUEL TANK 53% V FUELPUMP 74 75 (PRIOR ART) 78 80 79 F Aux. 46 AIR RUN/G MAlN/ AlR CLEANERTHROTTLE SWITCH l 45 ,40

1 SENSOR T ENRi lEl ViENT '52 56 3 I2 MEANs U 66 44 COMMANO UNIT OR a B60 T URE V REFERENCE sTANOARO 62 mm A US. Patent Nov. 18, 1975 Sheet 2of6 3,919,885

FIG. 2

TRIGGER CONTACTS l NTAKE MANIFOLD 10; 132% 06 36 IL? 255;

M I I I Lain) i 1 x38 1 n2 pm I 3 [00 H4 254 TEMPERATURE F|G 4 SENSOR 42COMMAND l I56 UNIT m 264 M5 FUEL INJECTOR I64 I60 '62 FIG 5 COIL @fi I66I72 T0 LAMP 202 2 mflwl E I f FUEL PUMP m? I70 F|G.6 i:

APPARATUS FOR DYNAMICALLY ANALYZING AN ELECTRONIC FUEL INJECTION SYSTEMAND THE ASSOCIATED ENGINE PARTS This is a continuation of applicationSer. No. 237,828, filed Mar. 24, 1972, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to apparatus for detecting defects within an electronic fuelinjection system and, in particular, to apparatus of the above typewhere the defect detection occurs while the engine is running andwithout interfering with the operation of the engine and the fuelinjection system.

2. Discussion of the Prior Art Electronic fuel injection systems areknown and have been described in various US. Pat. such as Nos. 2,883,976granted to S. G. Woodward et al.; 3,460,520 granted to R. Huber; and3,463,130 granted to W. Reichardt et al. Further, patents have beengranted on various systems for monitoring various aspects of internalcombustion engines and the like such as US. Pat. Nos. 3,358,499 grantedto G. Fourtane; 3,456,497 granted to E. Eberl; 3,512,405 granted to D.Schlicher; and 3,572.l03 granted to J. Marino.

However, heretofore, the apparatus utilized to monitor the performanceof electronic fuel injection systems has essentially done so on a staticbasis.

SUMMARY OF THE INVENTION In contradistinction to the known statictesting systems for electronic fuel injection systems, the system ofthis invention dynamically monitors the fuel injection system in such away that there is no interference with the operation of the engine orthe fuel injection system. Further, the operating parameters of the fuelinjection system are so monitored that detected defects aresubstantially isolated in a particular portion of the system.

Thus, it is a primary object of this invention to provide apparatus fordynamically monitoring the performance of an electronic fuel injectionsystem without interfering with the operation of the engine or the fuelinjection system.

It is a further object of this invention to monitor the performance ofthe pressure sensor, temperature sensor, speed sensor, pressure switch,throttle switch, fuel pump, fuel injection valves, and command unit of afuel injection system to detect either mechanical or electrical failuresin the above elements or the engine such as vacuum losses.

It is a further object of the invention to provide a reference signalgenerator responsive to the sensors of the fuel injection system forisolating defects either in the ,bon waste, and prolongs the life of thefuel injection 'valve stem and seat.

Other objects and advantages of this invention will become apparent uponreading the appended claims in conjunction with the following detaileddescription and the attached drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block diagram of anillustrative overall embodiment of the invention.

FIG. 1A is a schematic diagram of a fuel injection system which may bein accordance with the prior art.

FIG. 2 is a combined block and schematic diagram of an illustrativeembodiment of the speed sensing circuitry of this invention togetherwith circuitry for indicating the status thereof.

FIG. 3 is a combined block and schematic diagram of the load conditionsensing means of this invention together with circuitry for indicatingthe status thereof.

FIG. 4 is a combined block and schematic diagram of the temperaturesensing means of this invention together with circuitry for indicatingthe status thereof.

FIG. 5 is a combined block and schematic diagram of illustrative fuelinjection means for use with this invention together with circuitry forindicating the status thereof.

FIG. 6 is a combined block and schematic diagram for circuitry forcontrolling a fuel pump in accordance with this invention.

FIG. 7 is a schematic diagram of the circuitry for detecting defectswithin a fuel injection system and associated parts of an internalcombustion engine.

FIG. 7A is a plan view of an illustrative display panel in accordancewith this invention.

' FIG. 8 is a combined block and schematic diagram of an illustrativeembodiment of a reference signal generator in accordance with thisinvention.

FIGS. 9 and 10 are combined block and schematic diagrams of illustrativeembodiments of details within the circuitry of FIG. 8.

FIGS. 11A through 11,] are waveforms illustrating the operation of thecircuitry of FIGS. 8 through 10.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTIONReferring to FIG. I there is shown an illustrative overall system blockdiagram of the invention. Sensors l0 sense load conditions, ambienttemperatures. and speed of an internal combustion engine. Sensors I0 areconnected to a command unit 12 or reference generator or referencestandard or reference generating means 14 through a switch 16. Thesensors 10 are also connected to analyzer or defect detecting means 18over line 20. Reference generator 14 and analyzer 18 collectivelycomprise the dynamic fuel injection analyzer of this invention and areindicated within the dotted block 22. Command unit 12 is connected tofuel injectors 24 through switch 26 which is ganged with switch 16.Reference generator 14 is also connected to fuel injectors 24 dependingon the setting of switch 16 over line 28. Either command unit 12 orreference generator 24 is connected to analyzer 18 over line 30, onceagain, depending on the setting of switches 16 and 26.

In operation, the system of FIG. 1 functions as follows. Normally theswitches 16 and 26 are set in the upward position so that sensors 10 areconnected to command unit 12 while unit 12 is connected to the fuelinjectors 24. Hence, in this first mode of operation, referencegenerator 14 is not in the circuit. The analyzer 18 is responsive to thesensing signals generated by sensors 10 and the command or controlsignals generated by unit 12 to energize the fuel injectors 24. Hence,any defects in either the sensors 10, command unit 12, fuel injectors 24or the engine can be detected and analyzed 3 by unit 18. In order tofurther isolate any defects detected by analyzer 18, the switches 16 and26 are switched to the position shown in FIG. I. The sensing signals arethen applied to reference generator 14, which, in response thereto,generate control signals for the fuel injector over line 28, thesesignals also being applied to analyzer 18 over line 30. Since it isknown beforehand that the control signals produced by generator 14 arenot defective, it can be assumed that the defect. if still detected byanalyzer 18, is in the enginethat is. either in the sensors or the fuelinjectors 24.

Referring now to FIG. 1A, there is shown an electric fuel injectionsystem of the prior art. which illustrates in diagrammatic detail thevarious sensors incorporated within the block 10 of FIG. 1 together withan illustrative fuel injection device. The engine speed is detected byspeed sensing means 32 connected to the engine distributor. which willbe discussed in further detail hereinafter. The speed sensing meansapplies a speed sensing signal over line 34 to command unit 12, which,as indicated hereinbefore. may be replaced by reference generator 14.The load conditions of the motor are sensed by pressure sensing means36, which measures the vacuum in the air intake manifold 38 and inresponse thereto applies a load condition sensing signal over line 40 tothe command unit 12. The ambient temperature is measured by temperaturesensing means 42 which generate a temperature sensing signal which isapplied over line 44 to command unit 12. Sensing means 42 will bedescribed in more detail hereinafter. The air is induced into manifold38 through air cleaner 46 and throttle valve 48.

The position of throttle valve 48 is sensed by switch 50 to detectwhether it is open or closed and the signal generated by this switch isapplied to command unit 12 over line 52. A pressure switch 54 is alsoconnected to the air intake manifold and measures the difference betweenthe pressure therein and the outer atmosphere at full load to generate apressure difference signal which is applied over line 56 to command unit12.

The air drawn into manifold 38 is mixed with fuel injected by a fuelinjector valve 58. This valve is associated with one of the cylinders inthe car. Assuming a four cylinder car. the valves for the other cylinderare indicated at 60 through 64. Hence. valves 58 through 64 collectivelycorrespond to the injectors indicated at 24 in FIG. 1. These valves arecontrolled by control signals applied over lines 66, 68, and 72 fromcommand unit 12. It should be noted that in the prior art embodiment, asingle control signal is applied to a pair of valves whereas inaccordance with one aspect of this invention as will be brought out inmore detail hereinafter, separate. individual control signals arerespectively applied to each of the fuel injection valves regardless ofthe number of valves.

There is further shown in FIG. 1 a fuel tank 74 connected to fuel pump76 through fuel filter 78. Fuel for each of the cylinders is distributedthrough ring main 79, there only being shown in FIG. 1A the connectionto the first cylinder. A pressure regulator 80 maintains the pressure ata predetermined pressure such as 17 or 28 psi and enables excess fuel tobe returned to the fuel tank 74. The fuel pump is controlled fromcommand unit 12 over line 82.

Reference should now be made to FIG. 2 wherein there is shown in furtherdetail the relationship between the command unit 12 or referencegenerator 14 and the speed sensing means 32 together with means 4 fordetecting defects either in the unit 12 or the sensor 32, the defectdetecting means being generally indicated at 84. The speed sensor meansis part of the prior art and comprises first and second pairs ofcontacts 86 and 88, which are alternatively opened and closed by cammeans mounted in the lower section of the ignition distributor. Thefirst defect detecting means 84 comprises a resistor and a first statusindicating means 92, which is also indicated as M9. Status indicatingmeans 92 is preferably a modified ammeter which is responsive to theaverage value of alternative dc pulses applied thereto as will bebrought out in more detail hereinafter. The first status indicatingmeans also includes a second resistor 96 and a meter 98, which areprespectively identical to resistor 90 and meter 92. Meters 92 and 98are respectively associated with trigger contacts 88 and 86. Thedescription hereinafter will be mainly directed to meter 92 inasmuch asmeter 98 is the same as meter 92. In operation, the command unit 12applies over line 94 a first interrogation signal which typically is adc voltage to the contact pair 88. As contact pair 88 is successivelyopened and closed, a direct current pulse train will be applied overline 94 to command unit 12, which. in response thereto, will generatecontrol signals for the actuation of the fuel injectors. As will bebrought out in detail hereinafter, other sensing signals are alsoutilized to develop the control signals applied to the fuel injectors.

Assuming no defect is in the speed sensing system or in the engine. asmall amount of the pulse trains applied from contacts 88 will also beapplied to meter 92, the resistance 90 being so chosen that the defectdetecting circuit 84 does not interfere with the normal operation of thespeed sensing means. In other words, the resistance 90 is of asufficiently high magnitude to prevent undesirable loading of the speedsensing circuitry by the defect detecting circuitry. The signal appliedto meter 92 during normal operation causes the needle of the meter to beat substantially center scale at a predetermined engine speed.Typically, this speed might be 500 rpm. Thus, the meter 92 may becalibrated to provide a center scale reading for an engine speed of 500rpm.

Several of the possible defects which can occur in the speed sensingmeans 32 or the command unit 12 will now be discussed. First, if eitherof the contacts of contact pair 88 has been burned'thereby formingcorrosion, there will be an imbalance in the magnitude of the signalsapplied to command unit 12. Inasmuch as meter 92 reads the average dcvalue of the signal occurring on line 94, a deflection either right orleft of center on the scale of meter 92 will occur if the contact pair88 has become defective.

If an open circuit occurs in the line including contact pair 88, thiswill be detected immediately when the ignition switch is turned oninasmuch as the interrogation signal will be applied over line 94 andonly through meter 92 to effect full scale deflection thereof. Further,if a short circuit or leakage from one cable to the line includingcontact pair 88 occurs, the interrogation signal will be shorted toground thereby effecting little if any deflection of the meter 92.Further, the interrogation signal applied over line 94 may be defective,which will also be indicated on meter 92.

Hence, if defects are detected on meters 92 or 98, it can be immediatelyestablished that the defect is either in the speed sensor 32 or in thecommand unit 12. As described hereinbefore, the command unit 12 can beswitched out by switches 16 and 26 of FIG. 1 and replaced by referencegenerator 14. If the meters 92 or 98 still indicate a defect, then thedefect has been isolated in the speed sensor 32. However, if theindicators 92 or 98 indicate no defect, then the defect has beenisolated in the interrogation signals applied over lines 94 or 95.

Referring now to FIG. 3 there is shown a pressure sensor 36corresponding to that shown in FIG. 1. The pressure sensor 36 includes asubstantially air tight cylinder 100 which may include a diaphragm 102disposed in air tight relationship therein. The diaphragm 102 dividesthe cylinder 100 into two chambers 104 and 106. Chamber 104 is connectedto air intake manifold 38 by an appropriate coupling or line 108. Thediaphragm 102 is connected to core by rod 112. The core 110 is typicallymade of magnetic material and disposed between a primary winding 114 anda secondary winding 116 of a transformer 118. The command unit 12 or reference signal generator 14 applies an alternating current or pulses orsecond interrogation signal to primary winding 114 which are coupled tosecondary winding 116 and then returned to the command unit 12. Thesignal sensed across winding 116 has a parameter which is a function ofthe vacuum measured in intake manifold 38.

The foregoing is part of the prior art, however, a brief description ofthe pressure sensor will be given to facilitate understanding of theinstant invention and its efficacy in detecting defects in the pressuresensor and manifold. A second interrogation signal is applied to theprimary winding which tends to attract core 110 in the direction of thearrow A. However, this tendency is counteracted by the vacuum present inthe manifold 38 which tends to attract the diaphragm 102 in thedirection of the arrow B. Since the diaphragm and core are connected byrod 112, the diaphragm 102 stays in an equilibrium position as long asthe pressure or vacuum in manifold 38 remains constant. Referring toFIG. 1A, if throttle valve 48 is opened, thereby causing the pressure inmanifold 38 to decrease, there will be a tendency for the diaphragm 102to move in the direction of the arrow B. This will move the core 110thereby changing the load sensing signal applied across secondarywinding 116. This change in the load condition is sensed by command unit12 and utilized in the development of the control signals which areapplied to the fuel injectors, which will be described in more detailhereinafter.

In order to detect any defects in command unit 12, pressure sensor 36 ormanifold 38, second defect detecting means 120 are utilized inaccordance with this invention. Second defect detecting means 120 comprises first and second Wheatstone bridges 122 and 124. The componentscomprising Wheatstone bridges are of the same type but may be ofdifferent values. Hence. the following discussion will be mainlydirected to Wheatstone bridge 122 will be briefly discussed. Wheatstonebridge 124 is connected across primary winding 114 and includes signaldiodes 126 and 128, second status indicating means or modified ammeter130, and resistors 132 and 134. Meter 130 reads aven age current appliedthereto and resistors 132 and 134 are so selected to correspond to apredetermined load condition in manifold 38 which is a function of theparticular kind of automobile with which the second defect detectingmeans is used. Typical values for these 6 resistors are given in FIG. 7which will be discussed in more detail hereinafter.

The Wheatstone bridge 122 comprises diodes 136 and 138, meter 140 whichis also included within the second status indicating means, andresistors 142 and 144.

Assuming normal operation of the pressure sensor, intake manifold, andcommand unit, the null-detection meters 130 and 140 will be positionedat substantially center scale for a predetermined load condition. If aleak occurs in diaphragm 102 the diaphragm will move in the direction ofthe arrow B toward the extreme left of cylinder 102. This will unbalancethe signals occurring at diodes 126 and 128 such that the meter 130 willindicate a full scale reading and thereby indicate the diaphragm leak.

A further defect which may occur is a leak in the manifold 38 orcoupling 108 thereby causing a vacuum loss. This causes the diaphragm102 to be pushed to the right of cylinder 100--once again, unbalancingthe signals occurring across and reflected back into primary winding 114so that the meter 130 is deflected in the direction opposite from thatfor a diaphragm leak. That is, the needle will be deflected in onedirection for a vacuum leak and in the other direction for a diaphragmleak. Further, an open circuit in the primary winding 114 is alsoindicated on meter 130 by a deflection in the same direction as occursfor a vacuum leak. An open circuit in secondary winding 116 is indicatedon meter 140 in thesame manner as an open circuit is indicated on meter130.

From the foregoing it can be seen that meters 130 and 140 can detectdefects either in the intake manifold 38, the pressure sensor 36 or thecommand unit 12. As discussed hereinbefore, the command unit 12 can bereplaced by the reference generator 14 to isolate the defect either inthe command unit or in the engine including the intake manifold 38 orthe pressure sensor 36.

Referring to FIG. 4 there is shown the temperature sensing means orsensor 42 which typically comprises a thermister 146, the resistance ofwhich is an inverse function of the sensed temperature. As will bebrought out in more detail hereinafter, at least two temperature sensorsare used in this invention and are typically placed in the air intakemanifold, the cylinder head. or the crank case. These sensors measureambient engine temperature and generate temperature sensing signalswhich are applied to command unit 12 in response to a thirdinterrogation signal applied thereto over line 148. The signal appliedfrom the command unit is typically a dc voltage and the sensing signalgenerated by sensor 42 results from the fact that the resistance of thethermister varies with temperature. A third defect detecting means isconnected across temperature sensor 42 and comprises resistor 152 andthird status indicating means or meter 154. Meter 154 is typically adirect current micro-ammeter and is calibrated so that as long as thesensed temperature is normal, a center scale reading is provided.However, if overheating occurs in any of the engine parts sensed by thetemperature sensors, the current through meter 154 will decrease becauseof the decrease in resistance of the thermister 146. A short circuitwould also cause a deflection in meter 154 corresponding to that ofoverheating. An open circuit in the line including thermister 146 willcause a full scale reading of the meter 154. However. since, when theengine is cold, the resistance of thermister 146 will be high andthereby also cause a full scale reading of meter 154, the meter 154 willnot reliably indicate an open circuit until the engine has reached itsnormal operating temperature.

Defects in the command unit 12 causing a defective interrogation signalon line 148 are also detected by meter 154. Hence, as describedhereinbefore. the command unit 12 may be replaced with the referencegenerator 14 to isolate the location of the defect.

Referring to FIG. 5, there is shown the energization coil 156 of a fuelinjector such as shown at 58 in FIG. 1A. The fuel injector ismagnetically operated and opens and closes depending on whether anenergization, control signal or pulse is applied to coil 156. A fourthstatus indicating circuit 158 comprising resistor 160 and fourth statusindicating means or meter 162 is connected across the fuel injector coil156 and is responsive to the control signals applied from command unit12 or reference signal generator 14. An illustrative value of resistor160 is given in FIG. 7 as is the case for the other resistors used inthe status indicating circuits of this invention. Those values are givenfor illustrative purposes only. Meter 162 is the same type of meter asmeters 92 and 98 described in connection with FIG. 2. Meter 162 is socalibrated that the center reading thereof corresponds to apredetermined engine speed, load condition, and ambient temperature. Anopen circuit in the line including fuel injector coil 156 causes a fullscale deflection of meter 162. Loose or corroded grounds will also causedeflection of meter 162 in the direction of a full scale reading. Thedeflection will typically not be as great with a corroded ground andthus, the amount of the deflection of the meter also tends to isolatethe particular kind of defect involved. A short circuit or leakage inthe line including coil 156 causes little if any deflection of the meter162. Thus. defect detecting means 158 is responsive to the controlsignals generated by command unit 12 or reference signal gen erator 14to detect defects either in the command unit or the fuel injectorsystem.

A further defect which can occur in the fuel injection system isinternal corrosion of the fuel injection nozzle.-

Means for detecting this are indicated at 164 which comprises a voltagesource 166 and momentary contact switch 168. By depressing switch 168 amomentary contact is established which causes a pulse to be applied tothe fuel injector coil 156. This pulse should then cause fuel to beinjected by the injector. Hence, if nozzle corrosion is present. thiswill be detected by the failure of the valve to inject the fuel whichcan be readily observed.

In first, second, third, and fourth status indicating means describedhereinbefore, the loading of these means on the operating sensors,command unit and fuel injection devices is negligible. Further, in allof these status indicating devices, a defect in either the sensors,command unit or fuel injection devices is detected. Thus. for example,if a short occurs in the output circuitry of the command unit, whichgenerates the control signals for the injectors, this also will bedetected by meter 162 whereby the short can be isolated in the commandunit by replacing it with the reference signal generator. After such areplacement, the status indicated by meter 162 will be normal and thusthe short will have been isolated in the command unit.

Reference should now be made to FIG. 6 which illustrates circuitry forenergizing the fuel pump 76 for a predetermined amount of time to bringthe pressure in 8 the fuel line up to rated pressure which may typicallybe 17 or 28 psi. The command unit 12 generates a pulse of predeterminedlength to energize relay 170 and close contact 172 thereby connectingthe pump to a source of dc voltage for the predetermined length of timeto thereby bring the pump up to rated pressure.

Reference should now be made to FIG. 7 which is a schematic diagram ofthe analyzer or defect detecting means 18 of FIG. 1. The circuitry ofFIG. 7 includes a B line 174 and a ground line 176. A meter 178 or M1 isconnected across lines 174 and 176 and indicates that the ignition keyhas been turned on and that defect detector 18 has received itsoperating voltage. The engine is then turned on and the various elementsof the fuel injection system are monitored as follows.

When the engine is started, the command unit 12 is responsive to thestarting solenoid or fuel enrichment means 45 of FIG. 1A to generate afuel enrichment signal which is applied to the fuel injectors. Thepresence of the fuel enrichment signal is detected at terminal 180 andamplified in amplifier 182 and applied to switch 184 to energize light186 or L2.

As will be brought out in more detail hereinafter, the defect detectingcircuitry 18 of FIG. 7 analyzes fuel injection systems of differingtypes. Thus, two types which are presently commercially available arethe socalled type III and type IV systems. However, it is to beunderstood that the defect detector 18 of the subject invention can beused with and adapted to any type of electronically controlled fuelinjection system. Hence, switch 188 or S2 is utilized to switch theanalyzer to either the type III or type IV mode of operation. Switch S2is ganged to switches 189, 190, 191, 192, 194, 196, and 198. Theswitches are shown in the type III mode position.

Terminal 200 is connected to command unit 12 as indicated in FIG. 6 toenergize lamp 202 or L1 to thereby indicate proper operation of the fuelpump relay 76 and the associated power input circuitry from the commandunit 12. The signal generated by command unit 12 is applied to amplifier204 and thence to switch 206 where lamp 202 is energized.

Terminal 208 is connected to line 52 which is connected to the throttlevalve switch 54 of FIG. 1A. The throttle valve switch controls thecutoff of fuel at typically 1800 rpm and the supply of fuel when coatingat typically 1250 rpm. The proper operation of switch 54 is detected bya signal applied to terminal 208 from the switch when the throttle valveis closed during idle, this signal being applied through switch 192 andamplifier 210 to switch 212 to energize fifth status indicating means orlamp 214 or L6. Defective operation of the throttle valve can thus bedetected if, after depressing the accelerator, the lamp 214 continues tolight. That is, the throttle valve should open upon depression of theaccelerator peddle thereby deenergizing lamp 214 and thus, a faultythrottle valve can be detected.

Defective components within the command unit 12 can also be sensed atlamp 214 since terminal 216 is connected thereto through amplifiers 218,220, and 222 and switch 212. Terminal 216 is connected to a floatingground in the command unit 12 to which all circuits are referred. Thus,breakdown of any compo nents in the command unit is sensed at terminal216.

Thus, in summary, with respect to lamp 214- or L6, this lamp should beon when the throttle valve is closed and off when the throttle valveopened in response to the depression of the accelerator. However, if thelamp remains on, this indicates either a faulty component within thecommand unit via terminal 216 or a faulty throttle valve or a vacuumleak via terminal 208.

Lamp 224 or L serves a function similar to lamp 214 except that lamp 224is associated with type IV systems and is connected to terminal 208through switch 192 (which would be in its lower position), amplifier 226and switch 228. Terminal 216 may also be connected to lamp L5 in amanner similar to the way in which it is connected to lamp 214, however,for purposes of clarity it is not indicated in FIG. 7.

Sixth status indicating means or lamp 230 or L7 is connected to terminal232 which in turn is connected to line 56 connected to pressure switch54 of FIG. 1A. The pressure switch generates a pulse of predeterminedwidth when the accelerator is so depressed as to place the engine underfull load condition such as a rapid start from standstill. The pressureon the high vacuum side of the throttle valve is then drasticallyreduced thereby causing pressure switch 54 to generate the abovementioned pulse and apply it to terminal 232 through switching contacts190, amplifier 234, and switch 236 to energize lamp 230. Hence, if lamp230 comes on when the accelerator is rapidly depressed, the pressureswitch is operating satisfactorily. However, if it does not come oneither the pressure switch is faulty or a vacuum leak has occurred inthe high vacuum side of the vacuum system. The throttle valve switch,discussed hereinbefore, is employed via lamps 224 or 214 to detectvacuum leaks in the low vacuum end of the vacuum system. The throttlevalve 48 divides the high vacuum end which is to the right in FIG. 1Afrom the low vacuum end of the system.

Referring again to terminal 232, when the system is in the type IV modeof operation, the switch contact 190 will be in downward position.However, in the type IV mode of operation the signal generated bypressure switch 54 is termed an acceleration enrichment signaNevertheless, this signal is equivalent to the signal applied to lamp230 or L7 in that it indicates that a full load condition has beensensed by the pressure switch. The acceleration enrichment signal isapplied through the downwardly disposed contact 190 through amplifier238 and switch 240 to lamp 242 or L3. Thus, L3 detects essentially thesame conditions as detected by L7 or 230, as described above. Lamp 244or L4 is connected to terminal 216 through switching contacts 189,amplifier 246 and switch 248. In the type IV embodiment additionalinformation regarding the acceleration enrichment is provided toterminal 216 and the presence of this information is indicated at lamp244 or L4. However, if the pressure sensor is faulty, this accelerationenrichment signal may not be applied to terminal 216 under full loadconditions and thus, lamp 244 would not be energized indicating a faultcondition.

The status indicating means for the speed, load condition, and ambienttemperature sensing means and fuel injection means describedhereinbefore with respect to FIGS. 3 through 6 are also shown in FIG. 7.Thus, terminals 250, 252, 254, 256, 258, 260 and 264 are shown in FIGS.2-5 and 7. Terminal 262 is con- ;nected to the second temperaturesensing means mentioned hereinbefore in connection with the descriptionof the temperature sensing circuitry of FIG. 4. Terminals 264 through270 are respectively connected to the drive circuits for the fourcylinders of the automobile, it of course being realized that the numberof such circuits could be expanded depending upon the number ofcylinders. Terminals 272, 274 and 276 are special input terminals usedfor type IV injection systems and do not form a part of this invention.Switch *278 or S1 when closed connects all lamps of the circuitry ofFIG. 7 to B to assure that the lamps have not burned out and also forreference purposes.

Referring now to FIG. 7A there is illustrated a typical display panelfor illustrating the conditions described hereinbefore and detected bythe circuitry of FIG. 7. Thus, on FIG. 7A the reference numeralscorrespond to the corresponding meters or lamps already described withrespect to FIG. 7. There is further shown on the display panel of FIG.7A a pump test switch which is utilized with the test describedhereinbefore with respect to circuit 164 of FIG. 5. The purpose of thepump test switch is to actuate means not shown to lower the fuelpressure to a certain level and then bring it back up again to therequired level to conduct the test described hereinbefore with respectto circuitry 164. The pump test switch is indicated at 280. The fuelpressure is indicated at gauge 282.

Reference should now be made to FIGS. 8-11 wherein it is describedcircuitry corresponding to an illustrative embodiment of the referencegenerator 14 of FIG. 1. The reference generator may have as its powersource an automobile battery 284, the output voltage of which isregulated by voltage regulator 286. The dc output voltage from thevoltage regulator is applied to an oscillator 288 which generates thesignal which is applied to the primary winding 114 of FIG. 3, which isincluded in the pressure sensor 32. The output of the pressure sensor isapplied to an AC to DC converter 34, the output of which isrepresentative of the sensed load condition in the air intake manifold,as discussed in detail hereinbefore. The output signal from converter290 is applied to a summing network 292 comprising resistors 294-298.Also applied to the summing network may be a dc signal from a sensor 300for sensing the height of the engine above sea level. Such sensors arewell known and generally are responsive to barometric pressure withrespect to a predetermined level such as sealevel. The use of the heightsensing signal permits optimization of the fuel/air ratio. Also appliedto summing network 292 is a temperature signal derived from temperaturesensors such as that described in FIG. 4. Thus, the temperature sensedin the cylinder head is applied as a dc voltage to resistor 302 whilethe temperature from the crank case or air intake manifold is applied toresistor 304. These resistors are connected to a noninverting input of adifferential type operational amplifier 306. An inverting input of theamplifier is connected to a reference signal established atpotentiometer 308. The above type amplifier is well known to those ofordinary skill in this art and generally discussed in ElectronicsEngineers Handbook, Landee, Davis, and Albrecht, I957, pp. l9-6 through19-1 1. The potentiometer 308 is so set that the voltage therefromcorresponds to a predetermined normal operating temperature for theparticular automobile being tested or operated. The operationalamplifier 306 produces a reference voltage when the sensing signalapplied from the temperature sensors through resistors 302 (which isconnected at its other end to terminal 260 of FIG. 4) and 304 equals inabsolute magnitude that produced by reference potentiometer 308.However, any deviation in the sensed temperature from the referencetemperature will produce a change in the output voltage level fromamplifier 306 which is applied to the summing network 302 and thence toanother differential type operational amplifier 310, the operation ofwhich is the same as that of amplifier 306. To the inverting input ofthe amplifier 310 is applied a reference voltage, once again dependenton the type of engine which corresponds to a predetermined, combinedload condition and temperature signal for the selected type ofautomobile. The reference voltage is selected by switch 312 from one ofthe voltage divider networks 314 through 320. Any deviation of thesignal applied from summing network 392 from the selected referencevoltage will cause a change in the output voltage level from amplifier310 on line 311. This change in output voltage is applied to a voltagecontrolled timing circuit 312, which will be described in more detailhereinafter in FIG. 9. Timing circuit 312 is also responsive to a timingsignal applied over line 313 from valve selection logic circuit 314 overline 316, which will be described in more detail hereinafter withrespect to FIG. 10. Logic circuitry 314 is responsive to distributorcontacts 86 and 88 in speed sensor 32 to develop the control pulsesapplied to fuel injectors 58 through 64.

Referring to FIG. 9 there is shown in more detail the circuitry ofvoltage controlled timing circuit 312. This circuitry comprises aflip-flop 318 having its SET input connected to line 316 from valveselection logic 314 of FIG. 8. The SET output of flip-flop 318 isconnected to an integrating circuit comprising resistor 320 andcapacitor 322. The output of the integrator is applied to a voltagecomparator circuit 324 such as described in Pulse and Digital Circuits"by Millman and Taub. McGraw Hill Book Company. Inc., 1956. pages 458484.The reference signal for the voltage comparator 324 is connected overline 311 from operational amplifier 310. The output from voltagecomparator 324 is applied over line 326 to the RESET input of flip flop218.

Reference should now be made to FIG. 11 for a description of theoperation of FIG. 9. In FIGS. 11A and 11B there is shown the signalsgenerated by contacts 86 and 88 and applied to lines 95 and 94 of FIGS.2 and 8. As will be brought out in more detail hereinafter means withinthe valve selection logic circuitry 314 generates the trigger pulsesshown in FIG. 11C at each transition of the speed sensing signalsgenerated on lines 94 and 95. These trigger signals occur every 90 andare applied to the SET input of flip-flop 318 of FIG. 9 to set theflip-flop and initiate charging of condenser 322. The setting offlip-flop 318 also causes a voltage pulse to be initiated on line 313which is applied to the valve selection logic 314 of FIG. 8. Assumingthat the first solenoid is to be driven, a first pulse is applied fromthe output of valve selection logic 314 to the circuitry for driving thesolenoid of fuel injection valve 58. This pulse is shown in FIG. 11F andthe leading edge thereof corresponds to the setting of flip-flop 318.

The setting of flip-flop 318 will also initiate charging of capacitor322 which charges up to the reference voltage value occurring on line311. The operation of the comparator 324 is such that when the voltagelevel on each of the input lines thereto is equal, a pulse is generatedwhich resets flip-flop 318. The resetting of flip-flop 318 correspondsto the trailing edge of the control pulse or signal applied to fuelinjector 58 and shown in FIG. 11F. Capacitor 322 starts to dischargewhen flip-flop 318 is reset. It will continue to discharge untilflip-flop 318 is again set by the next trigger pulse. Since the spacingbetween the pulses isa function of the sensed engine speed, the amountthat capacitor 322 discharges will vary according to engine speed andthus, the length of time it takes for the capacitor to recharge to thereference voltage will also vary according to engine speed. Since thereference voltage also varies according to pressure and temperature, thelength of the pulse generated by flip-flop 318 varies according topressure, temperature, and speed.

Reference should now be made to FIG. 10 which illustrates anillustrative embodiment of the valve selection logic circuitry 314 ofFIG. 8. The speed sensors 86 and 88 are respectively connected overlines 95 and 94 to generate the signals shown in FIGS. 11A and 11B and,lines 94 and95 being respectively labelled A and B. Invertors 326 and328 respectively provide A and B signals. These invertors may eachcomprise a single stage NPN transistor circuit (not shown) with thecollector connected to line 301 through a load resistor, the baseconnected through a biasing resistor to line 301, and the emitterconnected to ground.

The AA, B, and B signals are combined in different combinations in ANDcircuits 330, 332, 334 and 336 which respectively generate AB, AB, AB,and AB functions which are applied to OR circuit 338. The leading edgeof each of these functions is differentiated by a differentiatorindicated at 340 to provide the trigger pulses shown in FIG. 11C of thedrawing. The A, A, B, and B signals are also applied to AND circuits342, 344, 346 and 348 in the combinations indicated in FIG. 10. Further,to each of these AND circuits is also applied the SET output offlip-flop 318 of FIG. 9 over line 313. Thus, depending on which of the Aor B functions is occurring at a particular time one of the AND circuits342 through 348 will be selected thereby effecting distribution of thecontrol pulses to the solenoid drivers for the fuel injectors 58 through64.

In FIG. 10 the solenoid for fuel injector 58 is indicated at 156 andcorresponds to that also shown in FIG. 5. The driving circuit comprisesa transistor 358 having an integrating or pulse forming circuit 360connected to the base thereof. The integrating or pulse forming circuit360 comprises resistor 362 and capacitor 364 and operates on the inputpulse applied thereto as shown in FIG. 11F to shape the pulse to producethe pulse shown in FIG. 11G. Typically, the length of the pulse shown inFIG. 11F will vary depending on the reference voltage applied to line311 from the temperature and pressure sensors. It will also vary as afunction of the speed sensed by sensors 32. The pulse width variation istypically 8 to 12 milliseconds and may vary depending on the type ofengine. The RC time constant of pulse shaping circuit 160 is such thatthe rise time is typically 3 milliseconds and may vary over a range of2.5 to 3.5 milliseconds for certain types of engines.

The purpose of decreasing the rise time is to minimize the impact of thecontrol pulse on the fuel injection solenoid. That is, rather thanslamming the fuel injector on with a pulse having a substantiallyvertical leading edge, the solenoid is gently turning on therebyprolonging valve stem and valve seat life. Further, the engine operationis also smoothed out.

Further, by applying four separate pulses respectively to the injectors58 through 64 as is done in the reference generator of FIGS. 8 through11, more accurate timing of the injection of the fuel into the cylindersin relation to piston position can be obtained. Hence, this 13 alsoresults in smoother operation and more complete fuel combustion tolessen exhaust pollution such as by drocarbon waste.

From the foregoing description of the operation of the referencestandard, it should be understood that it may be used not only as areference standard in a dynamic fuel injection analyzing system asdescribed hereinbefore; but it may also be used as a command unit 12shown in FIG. 1 to operate and control the fuel injection system.

The line 301 is connected from the positive side of the voltageregulator and is utilized to provide either directly or indirectly thebias voltages for all of the blocks of FIG. 8. However, lines are shownconnected only to blocks 306 and 316. The bias voltage applied to theinput transistor (not shown) of controller 306 con nected to resistors302 and 304 is the beforementioned third interrogation signal while thebias voltage applied to the base of the transistor invertors 326 and 328of FIG. is the beforementioned first interrogation signal.

Numerous modifications of the invention will become apparent to one ofordinary skill in the art upon reading the foregoing disclosure. Duringsuch a reading it will be evident that this invention provides a uniquedynamic fuel injection analyzing system for accomplishing the objectsand advantages herein stated.

What is claimed is:

l. Defect detecting apparatus for use with an internal combustion enginecomprising means for sensing at least the speed, load condition,

and ambient temperatures of said internal combustion engine;

fuel injection means for injecting a variable amount of fuel into thecylinder of said engine in response to at least one control signal;

control means for generating said control signal in response to saidsensing means; and

defect detecting means responsive to said sensing means, said fuelinjection means, and said control means for dynamically detectingpredetermined defects within said sensing means, said fuel injectionmeans, and said control means while said engine is running withoutinterfering with the operation of said internal combustion engine, saidsens ing means, said fuel injection means and said control means, saiddefect detecting means including status indicating means responsive tosaid control signal applied to said fuel injection means for indicatingthe status of said fuel injection means or said control means, saidstatus indicating means, in response to said control signal, indicatingthe presence of an open circuit or very high resistance in said fuelinjection means and said status indicating means, in response to theabsence of said control signal, indicating either the presence of ashort circuit or very low resistance in said fuel injection means or adefect in said control means.

2. Apparatus as in claim 1 where said sensing means includes speedsensing means for generating a first sensing signal, the frequency ofwhich is a function of said engine speed and where said defect detectingmeans includes first status indicating means responsive to said firstsensing signal for indicating the status of said speed sensing means.

3. Apparatus as in claim 2 where said sensing means includes loadcondition sensing means for generating a second sensing signal, aparameter of which is a func- 14 tion of the load condition of saidengine and where said defect detecting means includes second statusindicating means responsive to said second sensing signal for indicatingthe status of said load condition sensing means.

4. Apparatus as in claim 3 where said sensing means includes temperaturesensing means for generating a third sensing signal, the magnitude ofwhich is a function of said ambient temperature and where said defectdetecting means includes third status indicating means responsive tosaid third sensing signal for indicating the status of said temperaturesensing means.

5. Apparatus as in claim 1 where said sensing means includes speedsensing means for generating a first sensing signal representative ofthe speed of said engine in response to a first interrogation signalapplied thereto from said control means and where said defect detectingmeans includes first status indicating means responsive to said firstsensing signal and said first interrogation signal for indicating thestatus of said speed sensing means or said control means.

6. Apparatus as in claim 5 where said speed sensing means includes meansresponsive to the rotation of the ignition distributor for generatingsaid first sensing signal, the frequency of which is a function of saidengine speed and where said first status indicating means includes meansresponsive to said first sensing signal for indicating the desiredpresence thereof whereby said first status indicating means, in responseto said first interrogation signal, indicates the presence of an opencircuit or very high resistance in said speed sensing means and saidfirst status indicating means, in response to the absence of said firstinterrogation signal, indicates the presence of a short circuit or verylow resistance in said speed sensing means.

7. Apparatus as in claim 6 where said means respon' sive to the rotationof the ignition distributor includes at least one pair of contactssuccessively opened and closed in response to said rotation to generatesaid first sensing signal and where the said very high resistancecondition indicated by said first status detecting means is corrosion ofsaid contact pair.

8. Apparatus as in claim 5 where said sensing means includes loadcondition sensing means for generating a second sensing signalrepresentative of the load condition of said engine in response to asecond interrogation signal applied thereto from said control means andwhere said defect detecting means includes second status indicatingmeans responsive to said second sensing signal and said secondinterrogation signal for indicating the status of said load conditionsensing means or said control means.

9. Apparatus as in claim 8 where said load condition sensing meansincludes pressure measuring means located in the intake air distributorof said engine for generating said second sensing signal, a parameter ofwhich is a function of the pressure, and where said second statusindicating means includes means responsive to said second interrogationsignal and said second sensing signal for indicating the desiredpresence thereof.

10. Apparatus as in claim 9 where said pressure measuring means includesl a transformer, to the primary winding of which is applied a secondcommand signal and from the secondary winding of which is connected saidsecond sensing signal to said control means, (2) an armature disposedbetween said primary and secondary windings and connected to a diaphragmslidably mounted in a substantially air-tight cylinder to divide saidcylinder into at least two chambers, and (3) means for connecting saidintake air distributor to one of said chambers and where said secondstatus indicating means includes null-detecting means connected acrosssaid primary winding for indicating the status of said pressuremeasuring means whereby leakage in said diaphragm causes saidnulldetecting means to move in a first direction and a vacuum leak oropen primary circuit causes said null detector to move in a seconddirection.

11. Apparatus as in claim 10 where said second status indicating meansincludes null-detecting means connected across said secondary windingfor detecting an open circuit in said secondary winding.

12. Apparatus as in claim 8 where said sensing means includestemperature sensing means for generating a third sensing signalrepresentative of said ambient temperature in response to a thirdinterrogation signal applied thereto from said control means and wheresaid defect detecting means includes third status indicating meansresponsive to said third sensing signal and said third interrogationsignal for indicating the status of said temperature sensing means orsaid control means.

13. Apparatus as in claim 12 where said temperature sensing meansincludes temperature-sensitive, resistive means located in the crankcase and cylinder head of said engine for generating said third sensingsignal, the magnitude of which is a function of said ambient temperatureand where said third status indicating means includes means responsiveto said third sensing signal for indicating the desired presence thereofwhereby said third status indicating means, in response to said thirdinterrogation signal, indicates the presence of an open circuit or veryhigh resistance in said temperature sensing means and said third statusindicating means, in response to the absence of said third interrogationsignal, indicates the presence of a short circuit or very low resistancein said temperature sensing circuit.

14. Apparatus as in claim 1 where said control signal generated by saidcontrol means is a pre-established, reference control signal forisolating any defects indicated by said fourth status indicating meansin said fuel injection means.

15. Apparatus as in claim 14 where said control means includes means forgenerating said reference control signal, said reference control signalgenerating means including means for generating a plurality of controlsignals respectively applied to a plurality of said fuel injection meanswhereby complete combustion in each of the plurality of cylindersconnected to said fuel injection means is enhanced so that exhaustpollution is lowered.

16. Apparatus as in claim 14 where said control means includes means forgenerating said reference control signal, said reference control signalgenerating means including means for shaping said reference controlsignal so that the leading edge thereof is gradually sloped whereby thelife of the valve stem and seat of said fuel injection means isprolonged.

17. Apparatus as in claim 14 where said control means includes means forsensing the height of said engine'with respect to a predeterminedaltitude for generating a height signal and means responsive to theheight signal and said sensing signals for generating said controlsignal.

16 18. Apparatus as in claim 1 where said sensing means includes meansresponsive to the position of a throttle valve in the air intakemanifold for generating a throttle valve sensing signal and where saiddefect detecting means includes fifth status indicating means forindicating the status of said throttle valve.

19. Apparatus as in claim 18 where said fifth status indicating means isa first lamp whereby a vacuum leak in the low vacuum end of said airintake manifold is detected by rapid, irregular flickering of said firstlamp.

20. Apparatus as in claim 1 where said sensing means includes secondpressure sensing means responsive to full load vacuum in the air intakemanifold for generating a full load vacuum sensing signal and where saiddefect detecting means includes sixth status indicating means forindicating the status of said second pressure sensing means.

21. Apparatus as in claim 20 where said sixth status indicating means isa second lamp whereby said second lamp indicates a vacuum leak in thehigh vacuum end of said air intake manifold, if present.

22. Apparatus as in claim 1 where said sensing means includes meansconnected to a floating ground within said control means for generatinga circuit imbalance signal whenever components within said control meansare defective and where said defect detecting means includes seventhstatus indicating means for indicating the status of said componentswithin said control means.

23. Apparatus as in claim 22 where said fifth and seventh sensing meansare included in a common status indicating means, the fifth statusindicating means being operative when the throttle valve is closed andthe seventh status indicating means being operative when the throttlevalve is opened.

24. Defect detecting apparatus for use with an internal combustionengine comprising means for sensing at least the speed, load condition,

and ambient temperatures of said internal combustion engine; 1

fuel injection means for injecting a variable amoun of fuel into thecylinder of said engine in response to at least one control signal;control means having at least one input terminal and at least one outputterminal for generating said control signal in response to said sensingmeans;

reference signal generator means having at least one input terminal andat least one output terminal for generating a reference control signalin response to said sensing means;

switching means for respectively connecting said sensing means and saidfuel injection means to said input and output terminals of said controlmeans in a first position of said switching means and for respectivelyconnecting said sensing means and fuel injection means to said input andoutput terminals of said reference signal generator means in a secondposition of said switching means; and

defect detecting means connected to said sensing means and said fuelinjection means, said defect detecting means being further connected tothe input and output terminals of said control means when said switchingmeans is in said first position for dynamically detecting any defectswithin said sensing means, said fuel injection means, and said controlmeans while said engine is running without interfering with theoperation of said internal combustion engine, said sensing means, saidfuel injection means and said control means. said defect detecting meansbeing connected to the input and output terminals of said referencesignal generator when said switching means is in said second positionfor dynamically isolating any detected defect to either said sensingmeans and said fuel injection means or said control means while saidengine is running.

25. Apparatus as in claim 24 where said sensing means includes speedsensing means for generating a first sensing signal, the frequency ofwhich is a function of said engine speed and where said defect detectingmeans includes first status indicating means responsive to said firstsensing signal for indicating the status of said speed sensing means.

26. Apparatus as in claim 25 where said sensing means includes loadcondition sensing means for generating a second sensing signal, aparameter of which is a function of the load condition of said engineand where said defect detecting means includes second status indicatingmeans responsive to said second sensing signal for indicating the statusof said load condition sensing means.

27. Apparatus as in claim 26 where said sensing means includestemperature sensing for generating a third sensing signal, the magnitudeof which is a function of said ambient temperature and where said defectdetecting means includes third status indicating means responsive tosaid third sensing signal for indicating the status of said temperaturesensing means.

28. Apparatus as in claim 27 where said control means includes means forgenerating a second interrogation signal and where said sensing meansincludes load condition sensing means for generating a second sensingsignal representative of the load condition of said engine in responseto said second interrogation signal applied thereto from said controlmeans and where said defect detecting means includes second statusindicating means responsive to said second sensing signal and saidsecond interrogation signal for indicating the status of said loadcondition sensing means or said control means.

29. Apparatus as in claim 28 where said load condition sensing meansincludes pressure measuring means located in the intake air distributorof said engine for generating said second sensing signal, a parameter ofwhich is a function of the pressure, and where said second statusindicating means includes means responsive to said second interrogationsignal and said second sensing signal for indicating the desiredpresence thereof.

30. Apparatus as in claim 29 where said pressure measuring meansincludes l a transformer, to the primary windin g of which is appliedsaid second command signal and from the secondary winding of which isconnected said second sensing signal to said control means, (2) anarmature disposed between said primary and secondary windings andconnected to a diaphragm slidably mounted in a substantially air-tightcylinder to divide said cylinder into at least two chambers, and (3)means for connecting said intake air distributor to one .of saidchambers and where said second status indicating means includesnull-detecting means connected across said primary winding forindicating the status of said pressure measuring means whereby leakagein said diaphragm causes said nulldetecting means to move in a firstdirection and a 18 vacuum leak or open primary circuit causes said nulldetector to move in a second direction.

31. Apparatus as in claim 30 where said second status indicating meansincludes null-detecting means connected across said secondary windingfor detecting an open circuit in said secondary winding.

32. Apparatus as in claim 28 where said control means includes means forgenerating a third interrogation signal and where said sensing meansincludes temperature sensing means for generating a third sensing signalrepresentative of said ambient temperature in response to said thirdinterrogation signal applied thereto from said control means and wheresaid defect detecting means includes third status indicating meansresponsive to said third sensing signal and said third interrogationsignal for indicating the status of said temperature sensing means orsaid control means.

33. Apparatus as in claim 32 where said temperature sensing meansincludes temperature-sensitive, resistive means located in the crankcase and cylinder head of said engine for generating said third sensingsignal. the magnitude of which is a function of said ambient temperatureand where said third status indicating means includes means responsiveto said third sensing signal for indicating the desired presence thereofwhereby said third status indicating means. in response to said thirdinterrogation signal, indicates the presence of an open circuit or veryhigh resistance in said temperature sensing means and said third statusindicating means, in response to the absence of said third interrogationsignal, indicates the presence of a short circuit or very low resistancein said temperature sensing circuit.

34. Apparatus as in claim 24 where said control means includes means forgenerating a first interrogation signal and where said sensing meansincludes speed sensing means for generating a first sensing signalrepresentative of the speed of said engine in response to said firstinterrogation signal applied thereto from said control means and wheresaid defect detecting means includes first status indicating meansresponsive to said first sensing signal and said first interrogationsignal for indicating the status of said speed sensing means or saidcontrol means.

35. Apparatus as in claim 34 where said speed sensing means includesmeans responsive to the rotation of the ignition distributor forgenerating said first sensing signal, the frequency of which is afunction of said engine speed and where said first status indicatingmeans includes means responsive to said first sensing signal forindicating the desired presence thereof whereby said first statusindicating means, in response to said first interrogation signal,indicates the presence of an open circuit or very high resistance insaid speed sensing means and said first status indicating means, inresponse to the absence of said first interrogation signal, indicatesthe presence of a short circuit or very low resistance in said speedsensing means.

36. Apparatus as in claim 35 where said means responsive to the rotationof the ignition distributor includes at least one pair of contactssuccessively opened and closed in response to said rotation to generatesaid first sensing signal and where the said very high resistancecondition indicated by said first status detecting means is corrosion ofsaid contact pair.

37. Apparatus as in claim 24 where said defect detecting means includesfourth status indicating means 19 responsive to said control signalapplied to said fuel injection means for indicating the status of saidfuel injecting means or said control means whereby said fourth statusindicating means, in response to said control signal, indicates thepresence of an open circuit or very high resistance in said fuelinjection means and said fourth status indicating means, in response tothe absence of said control signal, indicates either the presence of ashort circuit or very low resistance in said fuel injection means or adefect in said control means.

38. Apparatus as in claim 24 including an internal combustion engine andwhere said reference signal generator means includes means forgenerating a plurality of control signals respectively applied to aplurality of said fuel injection means whereby complete combustion ineach of the plurality of the engine cylinders connected to said fuelinjection means is enhanced so that exhaust pollution is lowered.

39. Apparatus as in claim 24 where said reference signal generator meansincludes means for shaping said reference control signal so that theleading edge thereof is gradually sloped whereby the life of the valvestem and seat of said fuel injection means is prolonged.

40. Apparatus as in claim 24 where said control means includes means forsensing the height of said engine with respect to a predeterminedaltitude for generating a height signal and means responsive to theheight signal and said sensing signals for generating said controlsignal.

41. Apparatus as in claim 24 where said sensing means includes meansresponsive to the position of a throttle valve in the air intakemanifold for generating a throttle valve sensing signal and where saiddefect de- 20 tecting means includes fifth status indicating means forindicating the status of said throttle valve.

42. Apparatus as in claim 41 where said fifth status indicating means isa first lamp whereby a vacuum leak in the low vacuum end of said airintake manifold is detected by rapid, irregular flickering of said firstlamp.

43. Apparatus as in claim 24 where said sensing means includes secondpressure sensing means responsive to full load vacuum in the air intakemanifold for generating a full load vacuum sensing signal and where saiddefect detecting means includes sixth status indicating means forindicating the status of said second pressure sensing means.

44. Apparatus as in claim 43 where said sixth status indicating means isa second lamp whereby said second lamp indicates a vacuum leak in thehigh vacuum end of said air intake manifold, if present.

45. Apparatus as in claim 24 including a floating ground within saidcontrol means where said sensing means includes means connected to saidfloating ground within said control means for generating a circuitimbalance signal whenever components within said control means aredefective and where said defect detecting means includes seventh statusindicating means for indicating the status of said components withinsaid control means.

46. Apparatus as in claim 45 where said fifth and seventh sensing meansare included in a common status indicating means, the fifth statusindicating means being operative when the throttle valve is closed andthe seventh status indicating means being operative when the throttlevalve is opened.

1. Defect detecting apparatus for use with an internal combustion enginecomprising means for sensing at least the speed, load condition, andambient temperatures of said internal combustion engine; fuel injectionmeans for injecting a variable amount of fuel into the cylinder of saidengine in response to at least one control signal; control means forgenerating said control signal in response to said sensing means; anddefect detecting means responsive to said sensing means, said fuelinjection means, and said control means for dynamically detectingpredetermined defects within said sensing means, said fuel injectionmeans, and said control means while said engine is running withoutinterfering with the operation of said internal combustion engine, saidsensing means, said fuel injection means and said control means, saiddefect detecting means including status indicating means responsive tosaid control signal applied to said fuel injection means for indicatingthe status of said fuel injection means or said control means, saidstatus indicating means, in response to said control signal, indicatingthe presence of an open circuit or very high resistance in said fuelinjection means and said status indicating means, in response to theabsence of said control signal, indicating either the presence of ashort circuit or very low resistance in said fuel injection means or adefect in said control means.
 2. Apparatus as in claim 1 where saidsensing means includes speed sensing means for generating a firstsensing signal, the frequency of which is a function of said enginespeed and where said defect detecting means includes first statusindicating means responsive to said first sensing signal for indicatingthe status of said speed sensing means.
 3. Apparatus as in claim 2 wheresaid sensing means includes load condition sensing means for generatinga second sensing signal, a parameter of which is a function of the loadcondition of said engine and where said defect detecting means includessecond status indicating means responsive to said second sensing signalfor indicating the status of said load condition sensing means. 4.Apparatus as in claim 3 where said sensing means includes temperaturesensing means for genErating a third sensing signal, the magnitude ofwhich is a function of said ambient temperature and where said defectdetecting means includes third status indicating means responsive tosaid third sensing signal for indicating the status of said temperaturesensing means.
 5. Apparatus as in claim 1 where said sensing meansincludes speed sensing means for generating a first sensing signalrepresentative of the speed of said engine in response to a firstinterrogation signal applied thereto from said control means and wheresaid defect detecting means includes first status indicating meansresponsive to said first sensing signal and said first interrogationsignal for indicating the status of said speed sensing means or saidcontrol means.
 6. Apparatus as in claim 5 where said speed sensing meansincludes means responsive to the rotation of the ignition distributorfor generating said first sensing signal, the frequency of which is afunction of said engine speed and where said first status indicatingmeans includes means responsive to said first sensing signal forindicating the desired presence thereof whereby said first statusindicating means, in response to said first interrogation signal,indicates the presence of an open circuit or very high resistance insaid speed sensing means and said first status indicating means, inresponse to the absence of said first interrogation signal, indicatesthe presence of a short circuit or very low resistance in said speedsensing means.
 7. Apparatus as in claim 6 where said means responsive tothe rotation of the ignition distributor includes at least one pair ofcontacts successively opened and closed in response to said rotation togenerate said first sensing signal and where the said very highresistance condition indicated by said first status detecting means iscorrosion of said contact pair.
 8. Apparatus as in claim 5 where saidsensing means includes load condition sensing means for generating asecond sensing signal representative of the load condition of saidengine in response to a second interrogation signal applied thereto fromsaid control means and where said defect detecting means includes secondstatus indicating means responsive to said second sensing signal andsaid second interrogation signal for indicating the status of said loadcondition sensing means or said control means.
 9. Apparatus as in claim8 where said load condition sensing means includes pressure measuringmeans located in the intake air distributor of said engine forgenerating said second sensing signal, a parameter of which is afunction of the pressure, and where said second status indicating meansincludes means responsive to said second interrogation signal and saidsecond sensing signal for indicating the desired presence thereof. 10.Apparatus as in claim 9 where said pressure measuring means includes (1)a transformer, to the primary winding of which is applied a secondcommand signal and from the secondary winding of which is connected saidsecond sensing signal to said control means, (2) an armature disposedbetween said primary and secondary windings and connected to a diaphragmslidably mounted in a substantially air-tight cylinder to divide saidcylinder into at least two chambers, and (3) means for connecting saidintake air distributor to one of said chambers and where said secondstatus indicating means includes null-detecting means connected acrosssaid primary winding for indicating the status of said pressuremeasuring means whereby leakage in said diaphragm causes saidnulldetecting means to move in a first direction and a vacuum leak oropen primary circuit causes said null detector to move in a seconddirection.
 11. Apparatus as in claim 10 where said second statusindicating means includes null-detecting means connected across saidsecondary winding for detecting an open circuit in said secondarywinding.
 12. Apparatus as in claim 8 where said sensing means includestemperature seNsing means for generating a third sensing signalrepresentative of said ambient temperature in response to a thirdinterrogation signal applied thereto from said control means and wheresaid defect detecting means includes third status indicating meansresponsive to said third sensing signal and said third interrogationsignal for indicating the status of said temperature sensing means orsaid control means.
 13. Apparatus as in claim 12 where said temperaturesensing means includes temperature-sensitive, resistive means located inthe crank case and cylinder head of said engine for generating saidthird sensing signal, the magnitude of which is a function of saidambient temperature and where said third status indicating meansincludes means responsive to said third sensing signal for indicatingthe desired presence thereof whereby said third status indicating means,in response to said third interrogation signal, indicates the presenceof an open circuit or very high resistance in said temperature sensingmeans and said third status indicating means, in response to the absenceof said third interrogation signal, indicates the presence of a shortcircuit or very low resistance in said temperature sensing circuit. 14.Apparatus as in claim 1 where said control signal generated by saidcontrol means is a pre-established, reference control signal forisolating any defects indicated by said fourth status indicating meansin said fuel injection means.
 15. Apparatus as in claim 14 where saidcontrol means includes means for generating said reference controlsignal, said reference control signal generating means including meansfor generating a plurality of control signals respectively applied to aplurality of said fuel injection means whereby complete combustion ineach of the plurality of cylinders connected to said fuel injectionmeans is enhanced so that exhaust pollution is lowered.
 16. Apparatus asin claim 14 where said control means includes means for generating saidreference control signal, said reference control signal generating meansincluding means for shaping said reference control signal so that theleading edge thereof is gradually sloped whereby the life of the valvestem and seat of said fuel injection means is prolonged.
 17. Apparatusas in claim 14 where said control means includes means for sensing theheight of said engine with respect to a predetermined altitude forgenerating a height signal and means responsive to the height signal andsaid sensing signals for generating said control signal.
 18. Apparatusas in claim 1 where said sensing means includes means responsive to theposition of a throttle valve in the air intake manifold for generating athrottle valve sensing signal and where said defect detecting meansincludes fifth status indicating means for indicating the status of saidthrottle valve.
 19. Apparatus as in claim 18 where said fifth statusindicating means is a first lamp whereby a vacuum leak in the low vacuumend of said air intake manifold is detected by rapid, irregularflickering of said first lamp.
 20. Apparatus as in claim 1 where saidsensing means includes second pressure sensing means responsive to fullload vacuum in the air intake manifold for generating a full load vacuumsensing signal and where said defect detecting means includes sixthstatus indicating means for indicating the status of said secondpressure sensing means.
 21. Apparatus as in claim 20 where said sixthstatus indicating means is a second lamp whereby said second lampindicates a vacuum leak in the high vacuum end of said air intakemanifold, if present.
 22. Apparatus as in claim 1 where said sensingmeans includes means connected to a floating ground within said controlmeans for generating a circuit imbalance signal whenever componentswithin said control means are defective and where said defect detectingmeans includes seventh status indicating means for indicating the statusof said components within said control means.
 23. Apparatus as in claim22 where said fifth and seventh sensing means are included in a commonstatus indicating means, the fifth status indicating means beingoperative when the throttle valve is closed and the seventh statusindicating means being operative when the throttle valve is opened. 24.Defect detecting apparatus for use with an internal combustion enginecomprising means for sensing at least the speed, load condition, andambient temperatures of said internal combustion engine; fuel injectionmeans for injecting a variable amount of fuel into the cylinder of saidengine in response to at least one control signal; control means havingat least one input terminal and at least one output terminal forgenerating said control signal in response to said sensing means;reference signal generator means having at least one input terminal andat least one output terminal for generating a reference control signalin response to said sensing means; switching means for respectivelyconnecting said sensing means and said fuel injection means to saidinput and output terminals of said control means in a first position ofsaid switching means and for respectively connecting said sensing meansand fuel injection means to said input and output terminals of saidreference signal generator means in a second position of said switchingmeans; and defect detecting means connected to said sensing means andsaid fuel injection means, said defect detecting means being furtherconnected to the input and output terminals of said control means whensaid switching means is in said first position for dynamically detectingany defects within said sensing means, said fuel injection means, andsaid control means while said engine is running without interfering withthe operation of said internal combustion engine, said sensing means,said fuel injection means and said control means, said defect detectingmeans being connected to the input and output terminals of saidreference signal generator when said switching means is in said secondposition for dynamically isolating any detected defect to either saidsensing means and said fuel injection means or said control means whilesaid engine is running.
 25. Apparatus as in claim 24 where said sensingmeans includes speed sensing means for generating a first sensingsignal, the frequency of which is a function of said engine speed andwhere said defect detecting means includes first status indicating meansresponsive to said first sensing signal for indicating the status ofsaid speed sensing means.
 26. Apparatus as in claim 25 where saidsensing means includes load condition sensing means for generating asecond sensing signal, a parameter of which is a function of the loadcondition of said engine and where said defect detecting means includessecond status indicating means responsive to said second sensing signalfor indicating the status of said load condition sensing means. 27.Apparatus as in claim 26 where said sensing means includes temperaturesensing for generating a third sensing signal, the magnitude of which isa function of said ambient temperature and where said defect detectingmeans includes third status indicating means responsive to said thirdsensing signal for indicating the status of said temperature sensingmeans.
 28. Apparatus as in claim 27 where said control means includesmeans for generating a second interrogation signal and where saidsensing means includes load condition sensing means for generating asecond sensing signal representative of the load condition of saidengine in response to said second interrogation signal applied theretofrom said control means and where said defect detecting means includessecond status indicating means responsive to said second sensing signaland said second interrogation signal for indicating the status of saidload condition sensing means or said control means.
 29. Apparatus as inclaim 28 where said load condition sensing means inclUdes pressuremeasuring means located in the intake air distributor of said engine forgenerating said second sensing signal, a parameter of which is afunction of the pressure, and where said second status indicating meansincludes means responsive to said second interrogation signal and saidsecond sensing signal for indicating the desired presence thereof. 30.Apparatus as in claim 29 where said pressure measuring means includes(1) a transformer, to the primary winding of which is applied saidsecond command signal and from the secondary winding of which isconnected said second sensing signal to said control means, (2) anarmature disposed between said primary and secondary windings andconnected to a diaphragm slidably mounted in a substantially air-tightcylinder to divide said cylinder into at least two chambers, and (3)means for connecting said intake air distributor to one of said chambersand where said second status indicating means includes null-detectingmeans connected across said primary winding for indicating the status ofsaid pressure measuring means whereby leakage in said diaphragm causessaid null-detecting means to move in a first direction and a vacuum leakor open primary circuit causes said null detector to move in a seconddirection.
 31. Apparatus as in claim 30 where said second statusindicating means includes null-detecting means connected across saidsecondary winding for detecting an open circuit in said secondarywinding.
 32. Apparatus as in claim 28 where said control means includesmeans for generating a third interrogation signal and where said sensingmeans includes temperature sensing means for generating a third sensingsignal representative of said ambient temperature in response to saidthird interrogation signal applied thereto from said control means andwhere said defect detecting means includes third status indicating meansresponsive to said third sensing signal and said third interrogationsignal for indicating the status of said temperature sensing means orsaid control means.
 33. Apparatus as in claim 32 where said temperaturesensing means includes temperature-sensitive, resistive means located inthe crank case and cylinder head of said engine for generating saidthird sensing signal, the magnitude of which is a function of saidambient temperature and where said third status indicating meansincludes means responsive to said third sensing signal for indicatingthe desired presence thereof whereby said third status indicating means,in response to said third interrogation signal, indicates the presenceof an open circuit or very high resistance in said temperature sensingmeans and said third status indicating means, in response to the absenceof said third interrogation signal, indicates the presence of a shortcircuit or very low resistance in said temperature sensing circuit. 34.Apparatus as in claim 24 where said control means includes means forgenerating a first interrogation signal and where said sensing meansincludes speed sensing means for generating a first sensing signalrepresentative of the speed of said engine in response to said firstinterrogation signal applied thereto from said control means and wheresaid defect detecting means includes first status indicating meansresponsive to said first sensing signal and said first interrogationsignal for indicating the status of said speed sensing means or saidcontrol means.
 35. Apparatus as in claim 34 where said speed sensingmeans includes means responsive to the rotation of the ignitiondistributor for generating said first sensing signal, the frequency ofwhich is a function of said engine speed and where said first statusindicating means includes means responsive to said first sensing signalfor indicating the desired presence thereof whereby said first statusindicating means, in response to said first interrogation signal,indicates the presence of an open circuit or very high resistance insaid speed sEnsing means and said first status indicating means, inresponse to the absence of said first interrogation signal, indicatesthe presence of a short circuit or very low resistance in said speedsensing means.
 36. Apparatus as in claim 35 where said means responsiveto the rotation of the ignition distributor includes at least one pairof contacts successively opened and closed in response to said rotationto generate said first sensing signal and where the said very highresistance condition indicated by said first status detecting means iscorrosion of said contact pair.
 37. Apparatus as in claim 24 where saiddefect detecting means includes fourth status indicating meansresponsive to said control signal applied to said fuel injection meansfor indicating the status of said fuel injecting means or said controlmeans whereby said fourth status indicating means, in response to saidcontrol signal, indicates the presence of an open circuit or very highresistance in said fuel injection means and said fourth statusindicating means, in response to the absence of said control signal,indicates either the presence of a short circuit or very low resistancein said fuel injection means or a defect in said control means. 38.Apparatus as in claim 24 including an internal combustion engine andwhere said reference signal generator means includes means forgenerating a plurality of control signals respectively applied to aplurality of said fuel injection means whereby complete combustion ineach of the plurality of the engine cylinders connected to said fuelinjection means is enhanced so that exhaust pollution is lowered. 39.Apparatus as in claim 24 where said reference signal generator meansincludes means for shaping said reference control signal so that theleading edge thereof is gradually sloped whereby the life of the valvestem and seat of said fuel injection means is prolonged.
 40. Apparatusas in claim 24 where said control means includes means for sensing theheight of said engine with respect to a predetermined altitude forgenerating a height signal and means responsive to the height signal andsaid sensing signals for generating said control signal.
 41. Apparatusas in claim 24 where said sensing means includes means responsive to theposition of a throttle valve in the air intake manifold for generating athrottle valve sensing signal and where said defect detecting meansincludes fifth status indicating means for indicating the status of saidthrottle valve.
 42. Apparatus as in claim 41 where said fifth statusindicating means is a first lamp whereby a vacuum leak in the low vacuumend of said air intake manifold is detected by rapid, irregularflickering of said first lamp.
 43. Apparatus as in claim 24 where saidsensing means includes second pressure sensing means responsive to fullload vacuum in the air intake manifold for generating a full load vacuumsensing signal and where said defect detecting means includes sixthstatus indicating means for indicating the status of said secondpressure sensing means.
 44. Apparatus as in claim 43 where said sixthstatus indicating means is a second lamp whereby said second lampindicates a vacuum leak in the high vacuum end of said air intakemanifold, if present.
 45. Apparatus as in claim 24 including a floatingground within said control means where said sensing means includes meansconnected to said floating ground within said control means forgenerating a circuit imbalance signal whenever components within saidcontrol means are defective and where said defect detecting meansincludes seventh status indicating means for indicating the status ofsaid components within said control means.
 46. Apparatus as in claim 45where said fifth and seventh sensing means are included in a commonstatus indicating means, the fifth status indicating means beingoperative when the throttle valve is closed and the seventh statusindicating means being operative when the throttle valve is opened.